A common problem encountered by conventional tractor-trailer cargo hauling vehicles is the effect of air resistance or drag when traveling down the road. Typically the trailer extends to a height far above the height of the tractor cab. Because such trailers include a planar front face which is normally perpendicular to the direction of travel, the front face of a trailer presents significant resistance to air flow when it is pulled on the highway.
Similar resistance to air flow is encountered when high loads are carried on flat bed trailers. Also, resistance to air flow is encountered at the sides of the front face of the trailer or the load being hauled.
Various types of air deflector arrangements have been previously used on tractors and trailers to reduce resistance to air flow. The simplest device which is commonly used is an air deflector rigidly mounted on the top of the tractor cab or sleeper compartment to deflect air upwardly. Although use of such a device is helpful when the tractor is towing a trailer having a high front face, such device is not helpful when towing a flat bed trailer with a load which does not extend above the tractor cab. Such a deflector does not reduce resistance to air flow at the edges of the forward end of the load being carried on the trailer.
Other types of air deflector systems are describe, for example, in U.S. Pat. Nos. 4,611,796; 4,629,241; 4,353,587, 4,611,847; 4,357,045; and 3,945,677, and in West German O.L.S. Nos. 2437075 and 2949128. Many of such systems are very expensive and cumbersome to install and use. As a result, they are not practical for most purposes. Furthermore, some such systems cannot be used in conjunction with flat bed trailers. Most of such systems require permanent attachment to the body of the tractor cab or the trailer and are not adaptable to various types of trailers to be towed by the truck tractor.
For example, some of the previous systems are designed only for use with a van type trailer of a specific height and width. In other words, many of such systems are custom made for a particular truck and a particular application. Thus, when the truck tractor is disengaged from a van type trailer and connected to a flat bed trailer (e.g., for hauling lumber or pipe), the air deflector system on the tractor may be inefficient or useless. Other systems intended for use with a van type trailer having a planar front face may not be appropriate for use with trailers having a refrigeration unit mounted on its front face.
Also, conventional air deflector systems are permanently mounted to the truck tractor cab or sleeper unit and accordingly cannot be easily removed. If they are removed there are numerous holes which must be filled to prevent moisture, dirt and air from passing through the holes in the cab or sleeper. Thus, as a practical matter, the air deflector system must remain with the truck tractor on which it is installed. This limits the adaptability of the truck tractor for use with a variety of trailers an loads.
There has not heretofore been provided an air foil system which can be effectively used on all types of truck tractors and which can be easily removed, if desired.